It is common for scar tissue to form at a surgical site within a patient's body, even after minimally invasive surgery. Depending upon the type and location of surgery, this internal scar tissue may tether adjacent blood vessels, organs, and other vital structures to the surgical bed. This can be undesirable because such tethering or adhesion may pull the vital structure out of position and/or subject the vital structure to stressing forces as the patient moves, possibly resulting in damage to the vital structure, the surgical site, or both. This undesirable adhesion is particularly pronounced when a prosthesis or other outside structure is implanted into the body. For example, adhesions tend to form between a lumbar prosthesis implant and the vena cava after anterior lumbar spine surgery, endangering the integrity of the patient's venous system.
In addition, the surgeon may desire to re-access the surgical site at a later date, for reasons including replacement of a deteriorated implant, repositioning of an implant, removal of an implant, performing a procedure at a surgical site adjacent to the previous site, and the like. Access for such revision surgery often requires that the surgeon painstakingly sever the adhesions while taking care not to damage the vital structures or the implant. Thus, adhesions can add unwanted time and complexity to what may be an already lengthy and sophisticated procedure.
One method that has been proposed to avoid the formation of adhesions between two structures of the body (hereafter discussed as being an implant and an adjacent vital structure) is to provide an anti-adhesion membrane between the structures. Such a membrane commonly is a flexible, planar sheet of material, possibly including means for attachment to an adjacent body tissue via sutures, staples, or other anchors. Current anti-adhesion membranes operate by biological inhibition of the scar response, layering of a gelatinous or other biologically compatible area to allow controlled ingrowth of adhesions in a desired area, or both. However, the known membranes may still inhibit relative movement between the implant and the vital structure. Moreover, these membranes are intended for permanent implantation and often block access to the surgical site for future revision surgery.
Accordingly, it is desirable to provide a method and apparatus of an anti-adhesion membrane which allows relative movement between an implant and an adjacent vital structure, and which facilitates access and tissue manipulation for revision surgery.